I looked for a more specific thread for this but came up short. I'm a guy but I just found this and thought it was a perfect replacement for a pee funnel on playa, a little plastic device that let's you flat out pee standing up. You could use the urinal in a porta. http://www.sheweeusa.com/shop/

There's also the "Go Girl," and a few other brands. I like the Go Girl because it's made of silicone, so it molds to your body quite nicely. Plus you can boil it or put it in an autoclave. Hooray for pee funnels!